Goose barnacles in motion

Ok, so there had to be a video. Here are some of the goose barnacles (Lepas testudinata) that I found on Noordhoek beach last month. Bear in mind that they are out of their natural habitat (which is sea water) and were struggling in the sun. (I did try to drag some of the kelp back to the sea, but the pieces were huge and high up on the sand.) This group of barnacles was quite frisky, and shows you what a raft of kelp colonised by goose barnacles might look like if you swam underneath it.

For more on goose barnacles, visit this post.

Farewell (for now) to the short tailed stingrays

This my the final video (for now) of short tailed stingrays (Dasyatis brevicaudata) swimming under the boat on a sunny February day in between dives.

The IUCN Red List has these rays as of “least concern”, but they are protected in Western Australia because of their tourism value. There are locations in this region where tame stingrays interact with visitors; much like the rays at Struisbaai harbour.

More stingrays under the boat

We spent quite a bit of time with the short tailed stingrays (Dasyatis brevicaudata) between dives this past summer. Here’s another short video of one under the boat in shallow water.

These rays can grow to over two metres in diameter and weigh a few hundred kilograms at their maximum. They are a popular target for fishermen.

Stingray in the sunshine

Here’s another view of one of the short tailed stingrays (Dasyatis brevicaudata) in the sunshine last month. Surprisingly little is known about these animals. They’ve been studied in Australia and New Zealand where they are also found, but not much work has been done to learn about them here.

If you have watched the original BBC Blue Planet series (if you haven’t, why not?) you will have seen the massive aggregations of these rays that form at the Poor Knights Islands off New Zealand. I wonder if there are any similar aggregations off the South African coast that we don’t know about?

Watching stingrays from the boat

We visited this beautiful short tailed stingray (Dasyatis brevicaudata) near Millers Point between dives one day in mid February. They’re commonly seen during the summer months, when water temperatures in False Bay are between 16 and 22 degrees celsius.

I find them to be more curious about the boat than they are when we see them during dives. Then, they’re most often resting or eating on the sand, and after a short time they swim away.

Hunting rockcod and moray eel in Sodwana

This is a really cool bit of behaviour that I filmed on a dive to Pinnacles on Two Mile reef while we were in Sodwana last September, and one of my favourite things of all that we saw. A malabar rockcod (Epinephelus malabaricus) – as identified by our dive guides – in dark hunting colours, patrols the reef ahead of a honeycomb moray (Gymnothorax favagineus). At the time I didn’t know what was happening – it looked as though the eel was stalking the grouper – but it turns out to be more complicated and more interesting than that. I had filmed a subset of a total pattern of behaviour, in which the moray and rockcod (from the family of fish also called grouper) were hunting co-operatively.

A researcher at a Swiss university discovered in 2006 that coral groupers seek out giant moray eels (both of these species live in the Red Sea), summoning the eels from their dens with a vigorous shaking of their bodies. The fish and the eel then swim together looking for prey , a deadly tag-team of hunters. The groupers are fast in open water, but the eel can get into crevices to flush out prey. It is this behaviour, executed by a different type of eel and a different type of grouper, that I saw in Sodwana.

The scientists reported that the groupers use a head-stand signal, combined with a shaking of their bodies, to indicate the location of hidden prey to the eels. When the eels see this, most of them swim towards the grouper, and flushed out the prey.

You can read more about the study that revealed the extent of this behaviour here, and the actual paper reporting the research here. The scientists also discovered two other species with complementary skills that hunt co-operatively, on the Great Barrier Reef this time: the coral trout, and octopus.

Moray eels look incredible when they swim freely across the reef. Here’s one doing just that, in the Red Sea.

On the reef in Sodwana

We wrap up the videos from Sodwana with a couple of clips showing everyday life on the reef. Both these videos were filmed on a beautiful dive on Pinnacles, Two Mile Reef, which was strangely not marred by an absolute circus of an Open Water course that was being conducted in the vicinity. (Pinnacles is a popular training site.) Despite antics which included two people’s weight belts coming loose at the same time, we were able to stay away from that chaos and to enjoy some incredible reef life. (Perhaps I will share some footage of the weight belt fiasco when a suitable amount of time has passed.)

Clown triggerfish having a munch
Clown triggerfish having a munch

First up, a clown triggerfish (Balistoides conspiccillum) going about his business on the reef. These fish are fantastic looking, and if you ask Sophie nicely, she will show you the hand signal for them, which requires both hands to be free.

Here’s pair of barred filefish (Cantherhines dumerilii) at Pinnacles:

Schooling in Sodwana

In addition to lots of bluebanded snapper, we saw other schools of fish while we were diving in Sodwana. A calm approach with minimal body movement allows one to get quite close to them. Here, a school of lunar fuslier (Caesio lunaris) are led by a lone yellowback fusilier (Caesio xanthonota), filmed on Two Mile reef.

We also saw this school of handsome humpback snapper (Lutjanus gibbus) over Pinnacles on Two Mile Reef.

Reef life on Seven Mile in Sodwana

While we were in Sodwana in September, one of the dives I did was to Seven Mile Reef, which is further out and less busy than Two Mile. The dive was also slightly deeper than the Two Mile dives we did, which meant there was less surge and conditions were a bit easier all round.

We saw some lovely fish behaviour, and I’ll share two short videos taken with a new camera (more on that another time) to illustrate it. First, a redfang triggerfish (Odonus niger) slides its body into a crevice in the reef as I approach, to hide. This is typical behaviour when these fish are nervous.

Here’s a semicirle angelfish (Pomacanthus semicirculatus) concentrating very hard on feeding. These fish look like nothing so much as gorgeously decorated sheets of A4 paper with fins and a snout!

Snapper in Sodwana

Snapper are one of my favourite coral reef fish to dive with, because sometimes they’ll allow you into, or very close to, the dense schools they form over the reef. This must be what it feels like to be a fish, albeit one that breathes loudly and blows bubbles!

We saw these bluebanded snappers (Lutjanis kasmira) on a dive at Seven Mile Reef in Sodwana, last September. Notice the pair of Moorish idols (Zanclus cornutus) at the start of the video.

 Here’s another school of snapper we came across shortly after the first one. There are often other kinds of fish, including other types of snapper, in the school.

The Reef Guide is a good place to learn more about, and identify, the fish you see on dives off South Africa’s south and east coasts.